Tuned Fiber Optic Connectors

ABSTRACT

A method of tuning a fiber optic connector includes: assembling the fiber optic connector to a partially assembled state; tuning the fiber optic connector in the partially assembled state; assembling the fiber optic connector to an assembled state; and tuning the fiber optic connector in the assembled state.

BACKGROUND

Fiber optic cables are used in the telecommunication industry totransmit light signals in high-speed data and communication systems. Astandard fiber optic cable includes a fiber with an inner lighttransmitting optical core. Surrounding the fiber is an outer protectivecasing.

A fiber terminates at a fiber optic connector. Connectors are frequentlyused to non-permanently connect and disconnect optical elements in afiber optic transmission system. There are many different fiber opticconnector types. Some of the more common connectors are FC and SCconnectors. Other types of connectors include ST and D4-type connectors.

A typical SC fiber optic connector includes a housing having a front endpositioned opposite from a rear end. The front end of the SC connectorhousing is commonly configured to be inserted within an adapter. Anexample adapter is shown in U.S. Pat. No. 5,317,663, assigned to ADCTelecommunications, Inc. The SC connector typically further includes aferrule that is positioned within the front and rear ends of thehousing, and adjacent the front end. The ferrule is axially moveablerelative to the housing, and is spring biased toward the front of theconnector. The fiber optic cable has an end that is stripped. Thestripped end includes a bare fiber that extends into the connector andthrough the ferrule.

A connector, such as the connector described above, is mated to anotherconnector within an adapter like the adapter of U.S. Pat. No. 5,317,663.A first connector is received within the front portion of the adapter,and a second fiber is received within the rear portion of the adapter.When two connectors are fully received within an adapter, the ferrules(and hence the fibers internal to the ferrule) contact or are in closeproximity to each other to provide for signal transmission between thefibers. Another connector and mating adapter is shown in U.S. Pat. No.6,142,676, assigned to ADC Telecommunications, Inc.

Signal losses within a system often occur within the connection betweentwo optical fiber cores. Due to manufacturing tolerances of the ferruleouter diameter to inner diameter concentricity, ferrule inner diameterhole size and fiber outer diameter, and fiber core to fiber outerdiameter concentricity, when the fiber is inserted into the ferrule thecore of a fiber may not and typically does not end up perfectly centeredrelative to the ferrule outer diameter. If one or both of the fibers areoff center, when they are connected within an adapter, the fibers willnot be aligned and thus there will be a signal loss when the signal istransmitted between the two fibers. It is therefore desirable to tune aconnector to minimize this signal loss. Tuning can be accomplished bymeasuring signal characteristics through the connector and/or examiningphysical properties of the connector, and then determining the optimalposition of the ferrule and fiber in the connector.

SUMMARY

In one aspect, a method of tuning a fiber optic connector includes:assembling the fiber optic connector to a partially assembled state;tuning the fiber optic connector in the partially assembled state;assembling the fiber optic connector to an assembled state; and tuningthe fiber optic connector in the assembled state.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded view of an example fiber optic connector.

FIG. 2 is a side view of the connector of FIG. 1 in a fully assembledstate.

FIG. 3 is a cross-sectional view of the connector shown in FIG. 2.

FIG. 4 is a side view of the connector of FIG. 1 in a partiallyassembled state.

FIG. 5 is a cross-sectional view of the connector shown in FIG. 4.

FIG. 6 is a side view of the connector of FIG. 1 in a partiallyassembled state with a ferrule and hub of the connector pushed towards arear of the connector.

FIG. 7 is a cross-sectional view the connector shown in FIG. 6.

FIG. 8 is a side view of the connector of FIG. 1 in a fully assembledstate with the ferrule and hub pushed back towards a rear of theconnector.

FIG. 9 is a cross-sectional view of the connector shown in FIG. 8.

FIG. 10 is a cross-sectional view of the connector shown in FIG. 3.

FIG. 11 is a perspective view of the hub/ferrule assembly of theconnector shown in FIG. 1.

FIG. 12 is another perspective view of the hub/ferrule assembly of theconnector shown in FIG. 1.

FIG. 13 is a perspective view of the key member of the connector shownin FIG. 1.

FIG. 14 is another perspective view of the key member of the connectorshown in FIG. 1.

FIG. 15 shows a method for tuning a connector in a partially assembledstate.

FIG. 16 shows a method for tuning a connector in an assembled state.

FIG. 17 shows a method for tuning a connector in partially assembled andassembled states.

DETAILED DESCRIPTION

The present disclosure is directed towards systems and method for tuningfiber optic connectors. Although not so limited, an appreciation of thevarious aspects of the present disclosure will be gained through adiscussion of the examples provided below.

FIG. 1 is an exploded view of an example connector 100. The connector100 includes a front housing 110, a rear housing 140, and a boot 150.Also included is a hub/ferrule assembly 120 with a hub 122 and a ferrule124. The hub 122 includes an anti-rotation portion 128 and an elongatedcylindrical rear portion 123. The hub 122 is connected to the ferrule124, such as with adhesive or with an interference fit. A spring 130 isalso provided. A fiber optic cable 101 is shown including a fiber and ajacket 103. The connector also includes a key member 160.

In examples described below, the connector 100 can be tuned using aplurality of methods. For example, the connector 100 can be tuned byrotating the hub/ferrule assembly 120 to a desired orientation duringand/or after assembly. In another example, the key member 160 can beconnected to the connector 100 in a desired orientation to tune theconnector 100 after the connector 100 is assembled. Additional detailsregarding these tuning processes are provided below.

Referring to FIGS. 2-14, the connector 100 is tuned using a firstprocess. In this first process, the orientation of the hub/ferruleassembly 120 is manipulated. In the example shown, the first process isdone while the connector 100 is being assembled. However, as describedfurther below, in alternative embodiments, the first process can also beperformed after the connector 100 is assembled.

In FIGS. 2 and 3, the connector 100 is shown in a fully assembled state.The front housing 110 of the connector 100 extends along a longitudinalaxis 200 and defines an anti-rotation seat 112 and a cavity 114. Theferrule 124 extends through a front bore 116 of the front housing 110and includes a passage 166. The anti-rotation portion 128 of the hub 122is slidingly engaged along the longitudinal axis 200 in theanti-rotation seat 112.

In the example embodiment, the anti-rotation portion 128 is shaped in anoctagonal configuration (see FIGS. 10-12) and the anti-rotation seat 112defines a seat of a complementary geometry. At least two notches 180,181 form the anti-rotation seat 112 and engage the anti-rotation portion128 (see FIG. 10). The anti-rotation portion 128 and the anti-rotationseat 112 allow for sliding along the longitudinal axis 200, but preventrelative rotation. Other mating shapes and configurations are alsopossible. The elongated cylindrical rear portion 123 of the hub 122extends into the cavity 114 of the front housing 110. The hub 122includes a passage 119 extending along the longitudinal axis 200.

The spring 130 surrounds the elongated cylindrical rear portion 123 ofthe hub 122. The spring 130 is captured between the anti-rotationportion 128 and a surface 146 of the rear housing 140. The spring 130functions to bias the anti-rotation portion 128 of the hub 122 into theanti-rotation seat 112 of the front housing 110. Because the ferrule 124is connected to the hub 122, the spring 130 also functions to bias theferrule 124 in a forward direction through the front bore 116.

FIGS. 2 and 3 show the final assembled positions of the front and rearhousings 110 and 140. In the fully engaged position as shown, tabs 143on the rear housing 140 engage openings 118 in the front housing 110.

An interference fit also is present when the front and rear housings 110and 140 are partially inserted to allow for tuning and assembly of theconnector 100, as described below.

In FIGS. 4 and 5, the hub 122 and ferrule 124 are inserted into thefront housing so that the anti-rotation portion 128 of the hub 122 sitsin the anti-rotation seat 112 of the front housing 110. Although thespring 130 has been removed for clarity, it should be understood thatthe spring 130 surrounds the elongated cylindrical rear portion 123 ofthe hub 122.

The rear housing 140 is then partially slid into the front housing 110so that a portion 201 of the rear housing 140 at least partially remainsoutside of the front housing 110 and the tabs 143 of the rear housing140 remain spaced apart from the openings 118. In this configuration,the spring 130 is captured between the anti-rotation portion 128 of thehub 122 and the surface 146 of the rear housing 140, and the springbiases the anti-rotation portion 128 of the hub 122 into theanti-rotation seat of the front housing 110, thereby preventing rotationof the hub 122 and the attached ferrule 124. A sufficient interferencefit exists between the front and rear housings 110 and 140 so that thetwo parts are held together containing the spring 130, the hub 122, andthe ferrule 124. The front and rear housings 110 and 140 are pressedtogether in any convenient manner, such as with a press or clampingtool.

Referring now to FIGS. 6 and 7, with the front housing 110 and rearhousing 140 in the same relative position as in FIGS. 4 and 5, theferrule 124 and the hub 122 can be pushed back against the biasing forceof the spring 130 along the longitudinal axis 200 towards the rearhousing 140 so that the anti-rotation portion 128 of the hub 122 entersthe cavity 114 and completely clears the anti-rotation seat 112. Thereis sufficient distance between the anti-rotation seat 112 and thesurface 146 so that a rear end 205 of the elongated cylindrical rearportion 123 of the hub 122 remains spaced apart from the surface 146 ofthe rear housing 140. In this position, because the anti-rotationportion 128 of the hub 122 is no longer engaged in the anti-rotationseat 112 of the front housing 110, the ferrule 124 and the hub 122 canbe rotated about the longitudinal axis 200 to tune the connector 100 asdesired.

Tuning can be by any method useful to determine the desired rotationalposition of the ferrule 124 in the connector 100. Once the ferrule 124has been rotated to the desired rotational alignment, the ferrule 124can be released and the spring 130 can once again bias the anti-rotationportion 128 of the hub 122 into the anti-rotation seat 112 of the fronthousing 110 (similar to the configuration illustrated in FIGS. 4 and 5),thereby preventing further rotation.

To complete assembly of the connector 100, the portion 201 of the rearhousing 140 is slid into the front housing 110 so that the tabs 143enter the openings 118 to fully couple the rear housing 140 to the fronthousing 110. This is the configuration previously described in referenceto FIGS. 2 and 3.

In the completely assembled configuration, as shown in FIGS. 2 and 3,the longitudinal distance along the longitudinal axis 200 between theanti-rotation seat 112 and the surface 146 of the rear housing 140 isshortened. In this state, it is no longer possible to push the ferrule124 and the hub 122 along the longitudinal axis 200 back into the cavity114 far enough to allow the anti-rotation portion 128 of the hub 122 tocompletely clear the anti-rotation seat 112 of the front housing 110.This is illustrated in the completely assembled connector 100 of FIGS. 8and 9, wherein the ferrule 124 and the hub 122 are pushed back into thecavity 114 until the rear end 205 of the elongated cylindrical rearportion 123 of the hub 122 bottoms out against the surface 146 of therear housing 140.

The hub 122 and the ferrule 124 cannot travel any farther back along thelongitudinal axis 200 once the rear end 205 engages the surface 146. Inthis position, the anti-rotation portion 128 of the hub 122 cannotcompletely clear the anti-rotation seat 112 of the front housing 110,thereby preventing rotation of the hub 122 and ferrule 124 about thelongitudinal axis 200.

Therefore, in the fully assembled configuration of the connector 100shown in FIGS. 8 and 9, neither a pushing force applied to the ferrule124 nor a pulling force applied to the cable attached to the connector100 and translated through the optical fiber to the ferrule 124 cancause the anti-rotation portion 128 to completely clear theanti-rotation seat 112. This prevents rotation of the ferrule 124,thereby assuring that a fully assembled connector 100 will not becomeuntuned. Additional details regarding such a tuning method can be foundin U.S. Pat. No. 6,629,782 filed on Feb. 4, 2002, the entirety of whichis hereby incorporated by reference.

As shown in FIGS. 13-14, the key member 160 is placed onto the fronthousing 110 at the desired orientation to key the connector 100according to the tuned position. Specifically, the key member 160includes a rear opening 162 configured to receive the front housing 110in one of four orientations. The key member 160 is oriented so that akey protrusion 165 on the outer surface of the key member 160corresponds to the tuned position of the connector 100, and then the keymember 160 is slid onto the front housing 110 so that the front housing110 is positioned within the rear opening 162. For example, the keyprotrusion 165 is positioned to correspond to the tuned orientation ofthe hub/ferrule assembly 120.

Once inserted, the front housing 110 is coupled to the key member 160.The ferrule 124 extends through a front opening 164 of the key member160 for mating with another connector. In this configuration, the keyprotrusion 165 marks the tuned orientation of the connector 100.Additional details regarding the key member 160 can be found in U.S.Pat. No. 5,212,752 filed on May 27, 1992, the entirety of which ishereby incorporated by reference.

As described above, this first process can be used to tune the connector100 during assembly. For example, referring to FIG. 15, a first process240 for tuning the connector 100 in the partially assembled state isshown. Initially, at operation 242, the connector 100 is tuned in thepartially assembled state as described herein. Next, at operation 244,assembly of the connector 100 is completed. Finally, at operation 246,the key member is placed on the connector at the desired orientation.

In a second process 250 shown in FIG. 16, the connector 100 can be tunedafter assembly. Specifically, the second process 250 is performed afterthe connector 100 is assembled. Initially, at operation 252, theassembled connector 100 is tuned using one or more known methods fortuning For example, the connector 100 can be tuned so that a preferredorientation from one of four for the front housing 110 is identified.Next, at operation 254, the key member 160 is attached to the connector100 at the desired orientation.

Referring now to FIG. 17, another method 300 for tuning is described. Inthis method 300, the first and second processes are combined so that theconnector can be tuned using either and/or both processes.

Initially, at operation 310, the connector 100 is tuned during assemblyof the connector 100. For example, the connector 100 can be tuned usingthe first process described herein. Next, at operation 312, theconnector 100 can be keyed by placement of the key member onto theconnector.

Next, at operation 314, the assembled connector 100 can be tuned usingthe second process. This can be done for a variety of reasons. Forexample, as noted below, the connector 100 could have been improperlytuned (e.g., which could be identified during testing of connectorperformance), or the connector could become detuned through use (e.g.,if the hub/ferrule assembly 120 is force back hard enough to clear theanti-rotation seat 112 and spun, detuning can occur). Finally, atoperation 316, the key member is placed at the desired orientation.

Operations 310, 312 and 314, 316 can be performed separately on selectedconnectors, or performed sequentially. For example, as noted below,tuning of the connector is flexible, allowing the connector to be tunedby either of the first or second processes. In addition, the connectorcan be tuned using both processes, if desired.

There are several advantages for a connector that can be tuned using avariety of methods. Tuning has the potential to enhance the performanceof the connector. Allowing multiple methods for tuning provides greaterflexibility during manufacture of the connector. For example, someconnectors can be tuned during manufacture, and other connectors can betuned after manufacture.

Further, the multiple methods allow for re-tuning of connectors asdesired. For example, a connector can be tuned during manufacture usingthe first process. At a later point, the connector can be re-tuned(e.g., if the connector was not properly tuned during manufacture orbecomes untuned during use) using the second process. Other advantagesmay be realized.

The connector can be tuned using a variety of methods. For example, theconnector can be tuned manually by an individual and keyed. In such aprocess, the individual can test the connector at a variety oforientations and select a desired orientation for keying. In anotherexample, the connector can be tuned using an automated process thatselects the desired orientation and keys the connector. Other processes,such as a hybrid approach using both automated and manual tuningmethods, can be used.

Although the examples shown herein illustrate an SC connector, otherconnector types can be used. For example, in alternative embodiments, anLC or LX.5 connector can be used, such as that illustrated in U.S. Pat.No. 6,629,782.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

1-20. (canceled)
 21. A fiber optic connector, comprising: a fronthousing including a bore with an engagement surface, an anti-rotationseat, and defining a cavity; a fiber; a ferrule holding the fiber; a hubretainably engaging the ferrule, the hub including an anti-rotationportion; a rear housing including a bore; a spring positioned to pushthe anti-rotation portion of the ferrule into the anti-rotation seat ofthe front housing to resist rotation of the ferrule relative to thefront housing; and a key member; wherein the bore of the rear housing ispartially insertable into the bore of the front housing to form apartially assembled state; wherein the hub is pushable against thespring into the cavity so that the anti-rotation portion clears theanti-rotation seat of the front housing to allow the ferrule and the hubto be rotated to tune the fiber optic connector; wherein the rearhousing is pushable further into the front housing until the rear andfront housings are fully engaged to form a fully assembled state; andwherein the key member is attachable to the front housing at one of aplurality of orientations to further tune the fiber optic connector. 22.The fiber optic connector of claim 21, wherein the anti-rotation portionof the hub defines a plurality of rotational orientations into which theanti-rotation portion can be accepted into the anti-rotation seat of thefront housing.
 23. The fiber optic connector of claim 22, wherein theanti-rotation seat includes at least two notches that engage theanti-rotation portion of the hub.
 24. The fiber optic connector of claim21, wherein the key member includes a key protrusion that indicates atuned orientation.
 25. The fiber optic connector of claim 24, whereinfiber optic connector is an SC type connector.
 26. The fiber opticconnector of claim 21, wherein the plurality of orientations is fourrotational orientations.
 27. The fiber optic connector of claim 21,wherein fiber optic connector is an SC type connector.